the physical geography," says Dr. Forry, we find that on the sea-coast of New England, the influence of the ocean modifies the range of the thermometer and the mean temperature of the seasons. Advancing into the interior, the extreme range of temperature increases, and the seasons are violently contrasted. Having come within the influence of the lakes, a climate like that of the sea-board is found; and proceeding into the region beyond the modifying agency of these inland seas, an excessive climate is again exhibited. The variations of the isotheral and isocheimal curves--the lines of equal summer and of equal winter temperature,as illustrated in the map facing the titlepage-thus afford a happy illustration of the equalizing tendency of large

bodies of water."

Here are, then, four striking peculiarities of climate on the same parallels, within a comparatively limited space-that of the ocean and the lakes being characterized as uniform, and that of the intervening tract and the region beyond the lakes, as excessive or rigorous, climates. As in positions remote from large bodies of water the winters are colder and the summers hotter than in the opposite localities in the same latitude it is obvious that a classification of climates having for its basis mere latitude, is wholly inadmissible; for, although there may be no difference in the mean annual temperature, yet the distribution of heat among the seasons may be widely unequal. Did our limits permit, many other pe

Fort Wolcott, Newport, R. I.,
Fort Trumbull, New London, Conn.,
Council Bluffs, near the confluence of
Platte and Missouri,

Fort Armstrong, Rock Island, Ill.,

The meteorological phenomena of Canada, Nova Scotia, New Brunswick, and Newfoundland, according to the data furnished by the British army statistics, are in perfect harmony with the laws of climate developed in the United States.

"As Nova Scotia," says Dr. Forry, "is perfectly insular, with the exception of a neck of land eight miles wide, and is so much intersected by lakes and bays, that nearly one-third of its surface is under water, the mercury

culiarities in these systems of climate might be profitably introduced. A marked distinguishing feature, for example, between the climates peculiar to these large bodies of water and those in opposite circumstances, is the difference between the mean temperature of winter and spring, which, on the ocean and lakes, is only 17°, whilst in the opposite localities it is as high as 31o on the same parallel of latitude. This peculiarity in the increase of the temperature of spring, as manifested in the vegetable kingdom, constitutes a feature which strongly characterizes excessive climates; for, as Humboldt remarks," a summer of uniform heat excites less the force of vegetation, than a great heat preceded by a cold season.” Accordingly we find that in these excessive climates, (unlike the uniform ones on the ocean and lakes, in which the air is moist and the changes of the seasons slow and uncertain), summer succeeds winter so rapidly that there is scarcely any spring, and vernal vegetation is developed with remarkable suddenness.

Another feature which characterizes these two systems of climate is the mean annual range of the thermome

ter.

The law regulating the extremes of temperature is beautifully illustrated in the results of the four following posts, which are all nearly on the same parallel of 41° 30', the first two being on the ocean, and the last two far in the interior, remote from large bodies of water:

seldom rises above 88° in summer, or sinks lower than 6o or 8o below zero in winter. Its climate consequently exhibits a marked contrast to that of Lower Canada on the same parallels. In Newfoundland, the climate is similar to that of Nova Scotia; but the summers, owing to the melting of the icebergs on the coast, are less warm, of shorter duration, and subject to more sudden vicissitudes. In Canada, remote from the lakes, the climate is of the most excessive character.

At Quebec, when walking along the streets, the sleet and snow frequently freeze in striking against the face; and here, too, the alternations of temperature are so sudden, that the mercury has been known to fall 70o in the course of twelve hours. Cold weather sets in as early as November, from the end of which month till May the ground remains covered with snow, to the depth of three or four feet. When the winds blow with violence from the north-east, the cold becomes so excessively intense, that the mercury congealed in the thermometer serves no longer to indicate the reduction of temperature. Wine and even ardent spirits become congealed into a spongy mass of ice; and as the cold still augments, there follows congelation of the trees, which occasionally burst from this internal expansion, with tremendous noise. During winter, the general range is from the freezing point to 30 below zero. The seasons do not, as in more temperate regions, glide imperceptibly into each other. In June, July, and August, the heat, which often attains 95 of Fahr., is frequently as oppressive as in the West Indies."

2. The Middle Division, as it is traversed by the Alleghany range of mountains, running parallel with the Atlantic Plain, affords abundant opportunities of determining the interesting question of the influence of elevation above the sea upon climate. This has been done, not only by means of thermometrical data, but by observing the diversities in vegetable geography on the same parallels. The general laws developed in the Northern Division are here corroborated. The fact that the climate of the region of the lakes on our northern frontier is not more contrasted in the seasons than that of Philadelphia, will appear strange at first view; but this inference was long since deduced from observing that similar vegetable productions are found in each, whilst the same plants will not flourish in the interior of New York, Vermont, and New Hampshire.

"The region of Pennsylvania," says our author," as though it were the battle-ground on which Boreas and Auster struggle for mastery, experiences, indeed, the extremes of heat and cold.

But proceeding south along the Atlantic Plain, climate soon undergoes a striking modification, of which

the Potomac River forms the line of demarcation. Here the domain of snow terminates. Beyond this point the sledge is no more seen in the farmer's barn-yard. The table-lands of Kentucky and Tennessee, on the other hand, carry several degrees farther south, a mild and temperate clime. Although few thermometrical observations have been made upon the tableland lying in the centre of the middle division, or upon the ridges which crest this long plateau, thus rendering it impracticable to determine fully the interesting question of their influence upon temperature, yet we are enabled to supply this deficiency, in some measure, by observations made upon the differences in vegetable geography. Thus, in Virginia, as the limits of the State extend quite across the great Apalachian chains, four natural divisions are presented, viz., 1. The Atlantic Plain, or tide-water region, below the falls of the rivers; 2. The middle region between the falls and the Blue Ridge; 3. The Great Valley, between the Blue Ridge and the Alleghany Mountains; and, 4. The Trans-Alleghany region, west of that chain. In each of these the phenomena of vegetation are modified in accordance with the climatic features. On the Atlantic Plain, tobacco is the principal staple; in the Great Valley, it is cultivated only in the southern portion; and beyond the Alleghany its culture is unknown. In the first only is cotton cultivated, and in its southern part quite extensively. In North Carolina, the Atlantic Plain extends from sixty to seventy miles from the coast, whilst the middle region, corresponding to that described in Virginia, gradually merges into the mountainous regions farther west. As these table-lands are elevated from one thousand to twelve hundred feet above the sea, upon which rise many high crests, one of which (Black Mountain) is the highest summit of the Alleghany system, the diversity of climate on the same parallel causes a corresponding difference in the vegetable productions. Whilst the lowlands yield cotton, rice, and indigo, the western high country produces wheat, hemp, tobacco, and Indian corn. In South Carolina three strongly marked regions are also presented; but as the temperature increases, as a general law, in proportion as we approach the

equator, cotton is cultivated throughout the State generally. Georgia, Alabama, and Mississippi, like the Carolinas, are divided into three welldefined belts, exhibiting similar diversities in vegetable geography. Cotton and rice, more especially the former, are the great agricultural staples; and on the Atlantic Plain of these three States, as well as its continuation into Florida and Louisiana (which last two will be more particularly adverted to in the southern division), sugar may be advantageously cultivated. In North Carolina and Virginia, the At lantic Plain forms, as it were, a chaos of land and water, consisting of vast swamps, traversed by sluggish streams, expanding frequently into broad basins, with argillaceous bottoms. Through out its whole extent, as already remarked, it is characterized by similar features, besides being furrowed with deep ravines, in which the streams wind their devious way. The hot and sultry atmosphere of these low-lands, in which malarial diseases in every form are dominant, contrasts strongly with the mild and salubrious climate of the mountain regions-results that will be developed more fully in the investigation of endemic influences."

3. The Southern Division.-On approaching our southern coast, climate experiences a most remarkable modification. The seasons glide imperceptibly into each other, exhibiting no great extremes. This is strikingly illustrated on comparing the difference between the mean temperature of summer and winter at Fort Snelling, Iowa, and at Key West, at the southern point of Florida, the former being 56° 60', and the latter only 11° 34. Compared with the other regions of the United States, the peninsula of Florida has a climate wholly peculiar. "The lime, the orange, and the fig," says our author, "find there a genial temperature; the course of vegetable life is unceasing; culinary vegetables are cultivated, and wild flowers spring up and flourish in the month of January; and so little is the temperature of the lakes and rivers diminished during the winter months, that one may almost at any time bathe in their waters. The climate is so exceedingly mild and uniform, that besides the vegetable productions of the Southern States renerally, many of a tropical character

are produced. The palmetto, or cabbage-palm, the live oak, the deciduous cypress, and some varieties of the pine, are common farther north; but the lignumvita, logwood, mahogany, mangrove, cocoa-nut, &c., are found only in the southern portion of the peninsula. In contemplating the scenery of East Florida in the month of January, the northern man is apt to forget that it is a winter landscape. To him all nature is changed; even the birds of the air-the pelican and flamingo-indicate to him a climate entirely new. The author being attached, in January, 1838, to a boat expedition, the double object of which was to operate against the Seminoles and to explore the sources of the St. John's, found, in the midst of winter, the high cane-grass, which covers its banks, intertwined with a variety of blooming morningglory (convolvulus). The thermometer at midday, in the shade, stood at 84° Fahr., and in the sun rose to 100°; and at night we pitched no tents, but lay beneath the canopy of heaven, with a screen, perhaps, over the face, as protection against the heavy dews. Notwithstanding the day attains such a high temperature, the mercury just before day-light often sinks to 45°, causing a very uncomfortable sensation of cold. Along the south-eastern coast, at Key Biscayno, for example, frost is never known, nor is it ever so cold as to require the use of fire. In this system of climate, the rigors of winter are unknown, and a smiling verdure never ceases to reign."

a

The climate of Pensacola and of New Orleans, in consequence of the agency of the Gulf of Mexico, and in regard to the latter the additional influence of large lakes, is nearly as much modified as similar parallels in East Florida. In summer, the mercury rises higher in most parts of the United States, and even in Canada, than it does along the coast of Florida. In six years' observations at Key West, it was never known to rise above 90°. There is little difference between the thermometrical phenomena presented at Key West and at Havana. In the West India Islands, the mean annual temperature near the sea is only about 80°. At Barbadoes, the mean temperature of the seasons is as follows: winter 76°, spring 79°, summer 81°, and autumn 80°. The temperature is re

markably uniform; for the mean annual range of the thermometer, even in the most excessive of the islands, is, according to the British army statistics, only 130, and in some not more than 4°. Contrast this with Hancock Barracks, Maine, which gives an annual average range of 118°; Fort Snelling, Iowa, 1199; and Fort How ard, Wisconsin, 123°! The peculiar character of the climate of East Florida, as distinguished from that of our more northern latitudes, consists less in the mean annual temperature, than in the manner of its distribution among the seasons. Thus, though the winter at Fort Snelling, Iowa, is 54° 10' colder than at Key West, yet the mean temperature of summer at the latter is only 8 64' higher. In like manner, although the mean annual temperature of Petite Coquille, Louisiana, is nearly 2o lower, that of Augusta Arsenal, Georgia, nearly 8° lower, and that of Fort Gibson, Arkansas, upwards of 10° lower, than that of Fort Brooke, Florida; yet, at all, the mean summer temperature is higher. We thus perceive the truth of the remark made by Humboldt, that the climate of the tropics is characterized much more by the duration of heat than its intensity. "A comparison of the climate of East Florida," says Dr. Forry, "with the most favored situations on the continent of Europe, and the islands held in highest estimation for mildness and equability of temperature, in regard to the mean temperature of winter and summer, that of the warmest and coldest months, and that of successive months and seasons, results generally in favor of the former. Thus it is demonstrated that invalids requiring a mild winter residence have gone to foreign lands in search of what might have been found at home, viz.: an evergreen land in which wild flowers never cease to unfold their petals."

Having thus completed our notice of Dr. Forry's special examination of the several systems of climate pertaining to our wide domain, we will bring under notice several farther subjects of a general character.

In regard to the extremes of heat and cold in the United States, it would be natural to expect that the severest cold would be registered at the most northern, and the greatest heat at the most southern posts. It is now, how

ever, proved by exact instrumental observations that this is not the case, as these are situated on large bodies of water; but that the western stations, Forts Snelling, Gibson, and Council Bluffs, remote from inland seas, are remarkable for extremes of temperature. The highest temperature in the shade noted at our various posts, was at Fort Gibson, Arkansas, on the 15th of August, 1834, when two thermometers, observed by Dr. Wright of the army, rose in the shade, carefully excluded from reflected or radiated heat, the one to 116°, and the other to 117° Fahrenheit. Although the mean annual temperature, in proceeding from the equator towards the poles, gradually diminishes, yet the thermometer scarcely mounts higher at the equinoctial line than under the polar circle. It has been remarked that on the coast of Senegal the human body supports a heat which causes spirits of wine to boil, and that in the north-east of Asia, it resists a cold which renders mercury solid and malleable.

Much diversity of opinion has existed, in regard to the month that expresses the nearest equivalent to the mean annual temperature. Whilst Humboldt maintains that it is the month of October, Kirwan shows by tabular statements, that April is better entitled to this characteristic. As the laws of nature are universal, these phenomena, like all others, must be susceptible of systematic arrangement. It has been reserved for Dr. Forry to decide this long contested question, a means of comparison doubtless heretofore unequalled being afforded by the diverse systems of climate presented in the United States, more especially on the same parallels in the northern division. Our author shows that in eacessive climates, the mean temperature of April is generally as high as that of the year, whilst that of October is considerably higher; and in regard to modified climes, he demonstrates that the former is generally as much lower as the latter is higher. Now this relation is precisely what might have been anticipated, because the vernal increase of temperature is always much greater in rigorous than in uniform climates. Hence it follows that in the former class of climates, April expresses a nearer equivalent, whilst in the latter, October gives an approximation